Using the definition of the base of a log:
According to this, c could be a negative number, here's why:
Let's try to find the following logarithm:
Using the definition of the base of a log:
We can express 8 as 2³:
Using the following property:
We can express the equation as:
From this, we can conclude that c = -3, therefore it is possible for x to equal a negative number.